Your vacuum test seems pretty good. I don't think that indicates a plugged
converter. Yes, I don't think 275\250 is very hot before the Cat.
I wish you would have said there was some very light gray coating around the
tips and electrodes. The absence of any may indicate not enough fuel
burning. Yes, I use AP's in both of mine, have for years. I think they get
very acceptable mileage, but I'm not saying they're the best.
That would be interesting if it is the Magnaflow that just can't meet our
requirements.???? Biff Byrum
----- Original Message -----
From: "rws" <rwsam2002@yahoo.com>
To: "DakotaTruck DML" <dakota-truck@dakota-truck.net>
Sent: Friday, September 28, 2007 2:50 PM
Subject: DML: Re: Re: 94 Dak 5.2L Cat Converter Air Pump or Air Switch
Valve?
>
> I did some more checking and it seems that the cat converter is bad or
> not doing a complete job of cleaning HCs and Nox.
>
> I did the vacuum test at the intake manifold and @ idle it's 19"/hg
> when I raise the throttle quickly it goes to zero, if I raise the idle
> to 1500-2000 rpms gradually the vacuum goes up about 4"/hg but in about
> 20-30 seconds drops back down to 19"/hg. There may be a plugged up
> converter that is causing this, right?
>
> I let it warm up for around 20 minutes and did a temperature test on
> the front and rear of the converter. There is only a 25oF difference,
> not the 50-100oF that I'm told by the Magnaflow Tech it is suppose to
> have. Also, I may not of got it hot enough because the two temps were
> 275/250oF.
>
> When I asked the Walker exhaust tech he said that the temp test was not
> that accurate nowadays because of changes to the core materials.
>
> The Dodge converter was 20" long and heavy. The Magnaflow is 12" and
> 7lbs. I called Walker Exhaust and they have a longer heavier unit and
> their brick is 13" whereas the Magnaflow was only 6". Total length of
> the Walker # 15042 is ~ 18-19" Anyway my NAPA store has it in stock
> and @ $110 with my AAA card (10% off)
>
> Warranty of the converter at Walkers is 25k miles or two years, I
> believe the others are a lot less, 6 months or something like that.
>
> I haven't tried it yet but there is a site www.smogtips.com that is
> suppose to have tech feedback via email.
>
> Just looking back at my old smog test results and at one time the HC
> was down to just 1 PPM for HC. When I'm standing next to the exhaust
> pipe, I can't smell anything abnormal. When I drive on the freeway I
> can smell other cars with pollution and that's mainly when traffic is
> in gridlock, which we have a lot of.
>
> I hope to get it back up to the 18mpg it once had. Last tank I got
> 12.6mpg and driving was 25% in the city and rest on the freeway.
>
> I have a vac pump and I'll check the EGR valve but don't expect it to
> have problems sine I last replaced it. Just checked the price at NAPA
> and they said $115. ouch!
>
> My ignition stuff looks OK by just looking how the plugs are burning
> the fuel. Which is a nice lite tan and clean porcelain and clean
> electrodes - using Autolite platinums. Do they get good or low mpg's?
>
> This is OT but does a lap top PC Oscilloscope converter or adapter
> exist? I was looking at a very nice SW/HW $200 OBDII Scanner from
> Autotap.com but want it to be useful for OBD 1 also. Btw, they have a
> great tutorial on Sensors.
>
> Going to NAPA now . . .
>
>
> Ron in Kali
>
> ===============================================
>
> Re: Re: 94 Dak 5.2L Cat Converter Air Pump or Air Switch Valve?
> From: Biff Byrum (bbyrum9@foothill.net)
> Date: Fri Sep 28 2007 - 16:10:26 EDT
>
>
>
> I'm sorry, I'm stumped. You seem to have done everything that you could
> that
> applies to the problem. Try plugging your question into a a good search
> engine and finding a forum where you can talk directly to pro
> mechanics. I
> know there are several free ones around.
>
> Your EGR should not be the cause, and no, 11 to 15k is well within it's
> operating life. But if you can get ahold of a vacuum pump, test it
> anyway.
> Do the one test with the engine running, 3 to 5 in. maximum to affect
> engine
> speed. Then with the engine stopped, put 15 in. on the EGR. See how
> long it
> holds that, it must not begin leaking down immediately. If there is
> something wrong with it, it was likely defective to begin with.
>
> I agree you should to the CAT temp test. And yes, Kalifornia has been
> "adjusting" the pass values for years. I had proof of that back in
> 1988. But
> try to get CARB to admit to that.
>
> One thing a good smog mechanic will do first is to pull the codes. They
> don't all set the light, but if they have occured in the last fifty key
> cycles, they are stored in memory. One other thing is to prod the O2S
> with
> the Snap-On meter. It gives him the values right on the screen that
> it's
> returning. Should be 0.2 to 0.8 volts constantly varying back and
> forth. And
> it should pass the 0.5 volt line so many times a second. I put one on
> my 95
> a few years back and it just plain shorted out. It was returning almost
> line
> voltage to the PCM.
>
> By the way, I've been told that you should consider maximum service
> life on
> both EGR's and four wire O2S's to be around 80K. Keep us informed,
> there's
> lots more of us who could end up in the same boat in the near future.
> We
> don't all just recycle our Dak's every 60K. Biff
> ----- Original Message -----
> From: "rws" <rwsam2002@yahoo.com>
> To: "DakotaTruck DML" <dakota-truck@dakota-truck.net>
> Sent: Thursday, September 27, 2007 2:36 PM
> Subject: DML: Re: 94 Dak 5.2L Cat Converter Air Pump or Air Switch
> Valve?
>
>>
>> Biff,
>>
>> Oil and filter was changed. Using oil branded for "older" vehicles. I
>> think they put some copper in the oil to keep it running quieter, but
> need
>> to verify.
>>
>> New O2S.
>> New ECT sensor.
>>
>> Used Chevron's injector cleaner just prior to test, about a month
> ago. a
>> BMW dealer says its the best they found to keep injectors running
> clean
>> not dripping and remove the built up carbon on pistons and valves.
>>
>> PCV valve cleaned and checked and I can hear it making noise with
> engine
>> running. Shop manual says this is a good sign.
>>
>> The EGR valve was replace 2-3 yrs or 11-15k miles ago. Maybe low oct.
>> fuel can make it dirty again? I don't know. I tried to clean the EGR
>> with solvents befor getting a new one. They are hard to clean so that
>> they shut completly and smoothly, that's why I just got a new one.
> How
>> long should they last?
>>
>> If I give up and take it to a CA certified smog mechanic, what will
> he do?
>> Anyone here in California? Have you noticed the smog test criteria
> for
>> the three elements gets lower the older the vehicle is?
>>
>> Ron
>> -----------------------------
>> Re: 94 Dak 5.2L Cat Converter Air Pump or Air Switch Valve?
>> From: Biff Byrum (bbyrum9@foothill.net)
>> Date: Thu Sep 27 2007 - 16:54:30 EDT
>>
>> Yeah, I had about the same results. Just passed by one. It's said
> that
>> leaky injectors and the O2S are the leading causes of HC failure.
>>
>> Excess carbon buildup in the chambers can cause this reading. Someone
>> sugested B-12 Total Combustion Chamber Cleaner. Also suggested was
>> changing the oil so the new oil can absorb more HC. Remember that you
> do
>> have that silly, prone to fail EGR on that engine. Also, new PCV
> valve?
>> Biff
>
>
>
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